Normal Rules Don't Apply
by siriuslymcfly
Summary: "Normally, Derek would know better than to disturb a teenager before 10 on a saturday, he lived with one after all and it wasn't that long ago he was one himself, but this was not a normal situation, and therefore normal rules didn't apply." De-aged!Isaac, kid!fic, Derek calls Stiles for help. Written for a tumblr prompt.


**Yes, this is a kid!fic and I'm not particularly fond of children, but I can't help it with Sterek. Prompt: ****_Can I get Sterek - Isaac is turned into a toddler/baby and Derek calls Stiles._**

* * *

"Derek it's 7am, you better have a damn good reason to be calling this early on a non-school day." Normally, Derek would know better than to disturb a teenager before 10 on a saturday, he lived with one after all and it wasn't _that_ long ago he was one himself, but this was not a normal situation, and therefore normal rules didn't apply.

"Stiles, you need to get over here. Now." And here was another rule being broken. Honestly, Derek wouldn't have phoned Stiles if he had been actually thinking clearly. He hated getting the human boy involved in all their supernatural business any more than he needed to be, because if anything were to happen to him, it would be Derek's fault; yet another person he cared about would be gone because of him. Not that he cared about the boy, much. Those feelings also were not normal and so Derek was constantly just pushing them away. It was Stiles himself who liked to say he would ignore a problem until it went away, and here was Derek applying that -questionable- advice. There was some shuffling on the other end of the phone, but Derek didn't hear any questions from Stiles like he had expected. He should just give up expecting things from the boy, he never followed through on them.

"I'll be there in ten minutes," was all Derek got before Stiles hung up.

Derek paced anxiously while he waited for Stiles to arrive. When he heard the familiar sound of the engine of that old jeep he was at the door before Stiles had even got out the car.

"Are you going to tell me what's going on now?" Stiles called as he made his way over to Derek, hands stuffed in his pockets of his wrinkled jeans. His t-shirt was also creased, and his hair looked like he had just been dragged through a hedge, backwards. Obviously, Stiles hadn't looked in a mirror before dashing out of the house. Derek wasn't complaining though. He still smelled like sleep, all warm and comforting and- _no. That was not the priority right now._

"You'll need to see it to believe it." That sparked Stiles' interest. He followed Derek into the man's apartment and towards his bedroom.

"If I didn't know you better I'd think you were trying to seduce me Mr Hale." Derek rolled his eyes and pushed open the door, revealing his perfectly tidy room. Perfectly tidy mainly because he didn't actually possess many things and the room was definitely lacking in furniture. The only things in there were his king sized bed and a dresser which held the few clothing items he had bothered to go out and buy. Stiles gasped when he took in what was lying on the bed. "Is that..?" Derek nodded and they both stared at the little boy nestled in Derek's blankets, snoring gently. He had a head full of golden brown curls and that unmistakable dented ear that could only belong to Isaac. "Derek, why is there a mini Isaac sleeping in your bed?" Derek rubbed a hand over his face and shook his head.

"We were just on a morning run and then suddenly there was a noise and then," he gestured to the little boy and Stiles frowned.

"Okay, so you didn't see who did this? You didn't ask them why the hell they'd turn one of your betas into a one year old?" Derek growled.

"No, otherwise I wouldn't have called you would I?" Stiles held his hands up in surrender. "How do you know he's one?" Derek shot at Stiles who had started edging into the room to get a closer look at Isaac.

"I don't, I'm just making an educated guess. He looks about one, and he-" but Stiles stopped when Isaac yawned widely and looked up at him, eyes large and frightened.

"Hey buddy," Stiles started, easing down onto his knees beside the bed so he wouldn't be standing over the scared child. Isaac stared at him unblinking. Derek watched as Stiles continues to talk. "You're okay, we're not going to hurt you," he said. "Well, I'm not. Derek over there may, but I'll protect you from him, don't worry." Isaac frowned.

"'er'k," he mumbled, obviously trying hard to form words after just waking up. Stiles leaned closer.  
"What was that Isaac?"

"'er'k," he said louder, pushing himself into a sitting position. Derek shifted in the doorway, catching the child's attention.

"Erica? You want Erica?" Stiles asked but Isaac started to fuss, reaching out towards Derek.

"'er'k! 'er'k!" He cried, falling forwards then sitting back up again. He started to crawl towards the end of the bed in an attempt to reach Derek, but Stiles caught him before he could fall.

"You want Derek?" As Stiles approached with an arm full of child, Derek backed away. "C'mon Derek, just take him, he doesn't bite." Stiles paused. "Okay maybe he does. Hey, do you reckon he's still a werewolf? Can you even be a werewolf at this age? A werebaby maybe? Is Isaac a werepup now?" Isaac was getting more and more distressed as Stiles rambled and Derek just took him so it would stop the noise. As soon as the child was in his arms he stood awkwardly, not sure what to do next. Stiles rolled his eyes.

"Didn't you mention once that you had to look after your little cousins when you were younger?" Derek froze. He had said that to Stiles, but only when he thought the boy hadn't been really listening. Stiles had been complaining about his family coming to visit last summer and he had just said it without thinking. Of course the boy would remember that.

"It's not the same," Derek grumbled. Isaac looked up at him questioningly.

"Yes it is Sourwolf. Now, you're his Alpha still, I bet that's why he asked for you. So get him to like me or whatever and I'll take him, or get over your baby problems and comfort the kid." Derek stared at Stiles' resolute expression then sighed.

"He does like you," he muttered before bringing Isaac closer to his body and pressing his face into his neck, making a few snuffling sounds. Isaac giggled and made his own, patting Derek's stubbly cheek with one of his chubby hands, and Stiles watched them with an unreadable expression.

* * *

They made a plan. Well, Stiles made a plan and Derek just agreed with him as he was too busy trying to keep the toddler from getting into too much trouble. It wasn't a particularly complex plan; in fact, it was mainly just keep Isaac from killing himself on something dangerously sharp in Derek's apartment while they waited out the spell or whatever had happened to him. Derek assumed it was witches. If it was, that would be handy, as their spells didn't last more than a couple of days at the most, so Isaac would only be stuck for that long. If it wasn't witches though, Derek didn't want to even think about having to try and deal with the situation. Stiles insisted they let the pack know what was going on, he even suggested they help out with looking after Isaac. Surprisingly, one look at the toddler trying to eat Stiles' t-shirt and they all went running, claiming they were all suddenly busy for the next few days.

"Your pack sucks," Stiles grumbled as he sat with Isaac on Derek's couch, absentmindedly rattling the toy in his left hand to keep the child entertained while he scrolled through the bestiary with his right. Derek paused and took in the sight, a warm tingling feeling creeping into his limbs at the scene before him. Isaac giggled at the toy and made another grab for it, only to have Stiles pull it out of his reach last minute. This continued until Derek realised he hadn't actually said anything in return to Stiles statement and said boy looked away from his laptop to stare at him. "What?" Stiles asked. Isaac clutched the toy and pulled, almost taking Stiles with it due to his werewolf strength. Derek couldn't help but laugh as Stiles flailed and only just managed to prevent himself falling off the couch. Isaac, hearing Derek laugh, let out another giggle then chucked the toy across the room. He looked at Stiles expectantly like he assumed Stiles would get up and fetch it for him. "Oh no," Stiles shook his head. "I'm not becoming your personal slave Isaac. You want the toy? You go get it." Isaac started to pout, eyes going all out puppy dog. "Nope! Not going to work buddy, Scott's been trying for years with that one!" Isaac's eyes started to water, and then suddenly his face crumpled and he was letting out wails that echoed around the open room. "Oh god, I made him cry. No, no Isaac don't cry, I'm sorry!" Stiles tried to pick the boy up but he pushed away and cried some more. Panicking, Stiles jumped up and grabbed the toy. He tried to hand it back to Isaac, but the boy was having none of it. Before Stiles could get any more worked up, Derek strode forward and pulled Isaac into his arms. Looking straight into the distraught face, he growled lowly. Isaac stopped crying.

"How did you do that?" Derek shrugged and put the boy back down again, and he went straight back to playing with his toy like nothing had happened.

"It's a wolf thing," was all Derek said on the matter.

* * *

The first night had been awkward at first, as Derek had no idea if Stiles expected to stay over or not. He was surprised the boy had stayed the entire day to help out, especially after the whole crying incident and then Derek sort of ignoring him for an hour after that. He couldn't decide if he wanted Stiles there or if he wanted him to go before his stupid feelings got any worse. It was bad enough dealing with them when Stiles was just being his clumsy, talkative self. Add a baby in his arms to that and it was nearly impossible for Derek to resist just crowding the boy against the nearest wall and kissing him senseless.

It turned out that Stiles felt it was necessary for him to stay until Isaac was back to normal, so when Isaac woke up that night Derek made a point of getting to the child before Stiles had, just so the boy would get some more rest. The next morning had been almost too domestic for Derek to cope with, and he had silently watched Stiles spoon feed Isaac some mushed up food that smelled even worse than it looked. They had Lydia to thank for that, since she was the _only_ one who had done _anything_ to help out at all. Her shopping trip had stocked up Derek's cupboards with enough baby stuff to feel a small army.

That day was spent similarly to how the previous one had been; Stiles researched all he could while they took it in turns to keep Isaac entertained and to feed him. Derek was glad his Aunt had taught him how to change a diaper when he was younger, because that was one thing Stiles had no clue about. Everything else though he seemed to be a natural at. When Isaac started whimpering, he would already know what the boy wanted, whether it was feeding or just a cuddle. Being a werewolf meant the child was in constant need of human contact. When Derek mentioned that, Stiles just laughed and said it was also just an Isaac thing too.

"Dude, Isaac is just as clingy now. You should see him when we have sleepovers. Not even Scott tries to spoon me when we share my bed." Derek hadn't meant to growl at that, but the idea of Isaac _or_ Scott in Stiles' bed made his blood boil. Thankfully, Stiles ignored him in favour of grabbing Isaac, throwing him over his shoulder and spinning around until the child screamed happily.

Derek made dinner that night and he could feel Stiles watching him but he didn't say anything. Once it was done, he insisted on feeding Isaac before eating his own food, and Stiles silently watched him do that too in between mouthfuls of rice and chicken. Then they talked. Actually talked about anything and everything; not just supernatural, but everyday things like college applications for Stiles and the idea of actually getting a proper job for Derek. As they talked, Derek decided Stiles wasn't nearly as superficial as everyone seemed to assume. He had known the boy had depth, but his intelligence shone through in conversation and his knowledge of life in general was refreshing. They had both experienced loss, and somehow that seemed to allow Derek to open up to the boy opposite him about his family he had lost.

After dinner, they migrated over to the couch and Derek stuck on some movie he wasn't planning on following. Isaac was nestled between him and Stiles, his head on Stiles' lap and his feet curled up against Derek's thigh. He was asleep within half an hour of the movie starting. Stiles was about to get up to put him to bed, but Derek stopped him with a hand on his shoulder. He kept his arm rested on the back of the couch, hand only inches away from Stiles' head and he relaxed back, listening to the beating of the two steady hearts beside him.

During his stay, Stiles was sleeping in Isaac's room with Isaac in an old cot Lydia had given them. Derek didn't like them being so far away, even though there was only a wall separating them. It took him a while to fall asleep, but he was woken again only an hour or so later by the creaking of his door. He heard soft footsteps pad towards his bed and he cracked an eye open to see Stiles with Isaac in his arms. "We couldn't sleep," the boy mumbled tiredly. Isaac looked like he had just been crying, and Stiles looked exhausted. "He was asking for you," he added, fighting off a yawn. Derek shifted so he could take Isaac and the child instantly calmed down enough to close his eyes. Just as Stiles turned to walk out, Derek spoke. He didn't think about his words before he said, "stay". Stiles froze. Derek cursed. He had pushed it too far. But then Stiles was turning around and shuffling over to the other side of his bed and actually sliding in under the covers and Derek just watched with wide eyes. Stiles lay his head on the pillow and closed his eyes.

"Your bed is way more comfy," he mumbled into the fabric and Derek chuckled hesitantly. Was he supposed to lie down too? Put Isaac back in his cot? "S'eep Derek," Stiles sighed out, voice slurred from drowsiness. So Derek placed the sleeping toddler between them and lay down facing Stiles. He could see the teenager's face relax through Isaac's unruly curls and he too relaxed, finally able to fall asleep instantly with the boy close by.

* * *

This happened the next two nights. They would go to bed in separate rooms, Isaac would wake up demanding Derek, and he wouldn't settle until they were both laying beside him in Derek's bed. On the fifth night of Isaac's de-ageing, Stiles didn't even bother to take Isaac into his room. He slipped into Derek's bed and was asleep before the Alpha even joined them. Derek liked seeing Stiles curled up next to the child in his bed, wrapped up in his scent and breathing deeply, heart rate calm for once. Derek wondered briefly if Isaac would remember any of what had happened the past few days when he finally changed back, but he didn't dwell on it. He just got into bed, careful not to disturb the two sleeping bodies, and drifted off with a real smile on his face.

Derek woke up uncomfortably warm the next morning. He could feel a hot body pressed against his side and he felt like he was about to fall off the edge of his bed. Peering through sleepy eyes, he found a head of curls, darker than before, in his face, only this time there was a considerable number more and the owner was snoring. Loudly. Isaac was back to full size, and he was spread eagle on the bed, taking up more room than Derek and Stiles combined. He grunted and rolled over, successfully awaking Stiles by pushing him onto the floor. The noise Stiles made woke Isaac and he sat up, rubbing his eyes and looking around, confused. "What-" He spotted Derek beside him, then looked over at Stiles sprawled on the carpeted floor and frowned. "Er, what happened?" Derek sighed, flung the covers off and went over to help a still disorientated Stiles off the floor.

"Thanks," he murmured, brushing himself off and Derek caught a light blush creeping up his neck.

"Okay, I've missed something here." Derek glanced from Isaac to Stiles, who just threw his head back and laughed.

"You sure did buddy," Stiles choked out, and Derek laughed too, simply because Stiles was clinging onto his arm and those _feelings_ were back again in full force.

"Why do I smell baby food? And why the hell was I sharing a bed with _you two_?!" Stiles just shook his head and looked to Derek to provide an answer. But Derek was too busy trying to talk himself out of doing what he so desperately wanted to. And he was losing. He was leaning closer to Stiles, and the boy wasn't moving away. He didn't move away at all, in fact. When their lips brushed, he actually moved forward, using the hand still on Derek's arm to pull the Alpha closer.

"Yeah, I definitely missed something," Isaac muttered.

* * *

**Tadaaa, had to finish off with a kiss, sorry. I wasn't going to at first, but then I was just like "hey! It's Sterek, no one will mind!" Hope you enjoyed and please excuse any mistakes, it's 3am here and I've been writing for 3 hours so I'm sort of brain dead now.**


End file.
